Is there a way to show in game time?
Display the in game time on a PS3?
As MrLemon said, you can craft a Clock that will show you the time-lapse between day and night.
Write/apply a mod that could get me the time?
You can't mod Minecraft on the PS3. The only editions that you can mod are the Pocket Edition (Android) and the Java Edition (Windows, Mac & Linux).